Below is what I need to do for my mittens. when I get to the part for the thumb gusset I am not sure what I should be doing.
I know how to M1 but I get confused where it says slip marker. Hope someone can explain it to a not so knowledgeable knitter.

Slip marker means you move the marker from the needle it's on to the other needle. This gets it out of the way before you do your next m1, and keeps the stitches separated by the marker the way the pattern calls for.

Knit all the way up to the 1st stitch.
Move the marker from the needle it's on to the other needle.
Do your make 1.
Knit all the rest of the stitches up to the 2nd marker.
Make 1 before you move the marker.
Move the second marker.
Continue on.

I am making mittens too and that's what I'm doing. I actually use the KRL increase so I had one extra stitch between the markers while I was working it..it just was a better fit. Then when I removed the thumb stitches to a waste yarn I only moved the correct number. It worked fine.

If you are following your pattern you will be increasing right next to the markers so it should be easy to remember.

__________________
Jan

When asking questions ALWAYS post the name and a link for the pattern if you have it.

I had a similar problem when I started knitting mittens (and anything else that required markers, for that matter!). They kept throwing me off - I'd lose stitches, add spares. They're supposed to make it easier - go figure! I got so fed up I just skipped the darn things and counted all my stitches. It worked fine if I made sure I kept count. I transfered mine to a huge safety pin - it was easier for me to work around something solid rather than waste yarn.